CN110850334A - Nondestructive testing method and device for CT secondary circuit state - Google Patents
Nondestructive testing method and device for CT secondary circuit state Download PDFInfo
- Publication number
- CN110850334A CN110850334A CN201911193212.5A CN201911193212A CN110850334A CN 110850334 A CN110850334 A CN 110850334A CN 201911193212 A CN201911193212 A CN 201911193212A CN 110850334 A CN110850334 A CN 110850334A
- Authority
- CN
- China
- Prior art keywords
- circuit
- secondary circuit
- equivalent
- inductance
- frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
The invention relates to a nondestructive testing method for the state of a CT secondary circuit and a nondestructive testing device for the state of the CT secondary circuit, which utilize the difference of frequency spectrum characteristics (amplitude-phase-frequency characteristics) of equivalent circuits of the CT secondary circuit in a high-frequency state to judge four conditions of the passage, the open circuit, the short circuit, the poor contact and the like of the CT secondary circuit. The invention avoids applying voltage and current to PT and CT secondary circuits by adopting a voltage and current generating circuit, avoids the damage of the CT secondary circuits caused by applying overvoltage and overcurrent, and realizes nondestructive detection. The invention can completely detect various states of the CT secondary circuit, avoids manual operation, is simple and quick, and avoids potential safety hazards existing in the detection process of operators.
Description
Technical Field
The invention relates to the technical field of CT secondary circuit detection, in particular to a nondestructive detection method for the state of a CT secondary circuit and a nondestructive detection device for the state of the CT secondary circuit.
Background
The electric power metering system is composed of an electric energy meter, a voltage transformer (PT), a Current Transformer (CT) and a secondary circuit (namely a metering circuit) for metering, if a fault occurs in a component group of the electric power metering system, the electric energy cannot be accurately metered, and loss is brought to an electric power enterprise or a power generation enterprise.
In addition, faults of a part of metering loops, such as open circuit of a CT secondary loop and short circuit of a PT secondary loop, can possibly cause mutual inductors to be burnt and exploded, and cause property loss and safety problems for power users; therefore, when the metering device is checked and accepted during anti-electricity-stealing treatment, failure of the metering device or new capacity increase, the loop detection of PT and CT is required.
The traditional detection method is that a voltage current generating circuit is adopted to apply voltage current to PT and CT secondary loops, and the on-off of the loops is judged according to the feedback condition of the voltage current. The method is easy to damage a secondary circuit caused by overvoltage and overcurrent.
In the other detection method, in the process of checking and accepting the device, a technician holds the universal meter by hand and tests one by one through short circuit. The method is time-consuming and labor-consuming, and has potential safety hazards because technicians are required to drill into the cabinet body for detection.
Moreover, the two detection methods cannot accurately judge whether the CT secondary circuit is in poor contact, so that the measurement circuit monitoring and fault judgment results are not ideal.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a nondestructive testing method for the state of a CT secondary circuit and a nondestructive testing device for the state of the CT secondary circuit, which can realize accurate and rapid automatic detection on various states of the CT secondary circuit.
The technical scheme of the invention is as follows:
a non-destructive testing method for the state of a CT secondary circuit is characterized in that a high-frequency signal is input in series to the CT secondary circuit and a feedback signal is received in series; judging an equivalent circuit of the CT secondary circuit according to the frequency spectrum characteristic of the feedback signal; and obtaining the states of the CT secondary circuits corresponding to the equivalent circuits of different types.
Preferably, the high frequency signal inputted in series is a frequency sweep signal of 1kHz to 100kHz, and the frequency is increased with equal difference.
Preferably, when the CT secondary circuit is a path, the CT secondary circuit is equivalent to an equivalent circuit of a resistor, a capacitor, and an inductor series network, and a spectrum characteristic map corresponding to the spectrum characteristic has a unique obvious resonance point.
Preferably, when the CT secondary circuit is a path, the equivalent input impedance ZinComprises the following steps:
r, C, L is equivalent resistance, equivalent capacitance, and equivalent inductance of the equivalent circuit respectively;
further, the input amplitude-frequency characteristic expression is as follows:
preferably, when the CT secondary circuit is in a poor contact state, the equivalent input impedance is larger than that in a path, the equivalent input impedance is increased, and the number of distinct resonance points in the spectrum characteristic diagram is larger.
Preferably, when the CT secondary circuit is open, the CT secondary circuit is equivalent to an open circuit, and the feedback information cannot be received, and there is no spectrum characteristic diagram.
Preferably, when the CT secondary circuit is short-circuited, the CT secondary circuit is equivalent to a short-circuit, and receives the full frequency band of the feedback signal.
A detection device for non-destructive conjecture of the state of a CT secondary loop comprises a main control module, a high-frequency signal generation module, a feedback signal receiving module and a coupling inductor, wherein two ends of a primary loop of the coupling inductor are respectively connected with the high-frequency signal generation module and the feedback signal receiving module, and two ends of a secondary loop of the coupling inductor are connected with the CT secondary loop to form a detection loop; the main control module is respectively connected with the high-frequency signal generating module and the feedback signal receiving module, and executes the nondestructive testing method to obtain the testing result of the state of the CT secondary circuit.
Preferably, the system also comprises a loop state display module, wherein the loop state display module is connected with the main control module and displays the detection result through an indicator light; the indicating lamp displays different marks corresponding to different types of CT secondary circuit states.
Preferably, when the CT secondary circuit is a path, the equivalent inductance of the equivalent circuit is:
wherein L is1Is an inductance of the secondary side of the current transformer, L2For detecting inductance of other devices in the loop, L4An inductance coupled to the primary side of the inductance, L3An inductance of the secondary side of the coupling inductance, L4Is an inductance coupled to the primary side of the inductance.
The invention has the following beneficial effects:
the nondestructive testing method and the nondestructive testing device for the state of the CT secondary circuit utilize the difference of frequency spectrum characteristics (amplitude-phase-frequency characteristics) of equivalent circuits of the CT secondary circuit in a high-frequency state, thereby realizing the judgment of four conditions of the CT secondary circuit such as open circuit, short circuit, poor contact and the like.
The invention avoids applying voltage and current to PT and CT secondary circuits by adopting a voltage and current generating circuit, avoids the damage of the CT secondary circuits caused by applying overvoltage and overcurrent, and realizes nondestructive detection.
The invention can completely detect various states of the CT secondary circuit, avoids manual operation, is simple and quick, and avoids potential safety hazards existing in the detection process of operators.
Drawings
FIG. 1 is a schematic circuit diagram of a nondestructive inspection apparatus;
FIG. 2 is a schematic diagram of an equivalent circuit with a CT secondary circuit as a pass-through;
FIG. 3 is a schematic diagram of an implementation of the nondestructive testing apparatus.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
The invention provides a nondestructive testing method for the state of a CT secondary circuit and a nondestructive testing device for realizing the nondestructive testing method, aiming at solving the defects of secondary circuit damage risk, detection type deficiency, complex operation, low efficiency, potential safety hazard and the like in the prior art. The invention can be automatically completed, and can detect the states of the CT secondary circuit in all types, including four conditions of access, open circuit, short circuit and poor contact.
The invention relates to a nondestructive testing method for CT secondary circuit state, which is technically characterized in that four conditions of CT secondary circuit path, open circuit, short circuit and poor contact are distinguished by utilizing different frequency spectrum characteristics (amplitude-phase-frequency characteristics) of equivalent circuits of CT secondary circuits in a high-frequency state. Specifically, a high-frequency signal is input in series in a CT secondary circuit and a feedback signal is received in series; judging an equivalent circuit of the CT secondary circuit according to the frequency spectrum characteristic of the feedback signal; and obtaining the states of the CT secondary circuits corresponding to the equivalent circuits of different types.
In this embodiment, the high-frequency signal input in series is a frequency-sweep signal of 1kHz to 100kHz, and the frequency is increased with equal difference, for example, the frequency-sweep signal is increased by 1kHz each time, and then the frequency-sweep signal is injected into the CT secondary loop through the amplifying circuit, and then feedback is formed.
In order to implement the nondestructive testing method, the invention also provides a testing device for the nondestructive conjecture of the state of the CT secondary loop, as shown in fig. 1, which comprises a main control module, a high-frequency signal generating module, a feedback signal receiving module and a coupling inductor, wherein two ends of the primary loop of the coupling inductor are respectively connected with the high-frequency signal generating module and the feedback signal receiving module, and two ends of the secondary loop of the coupling inductor are connected with the CT secondary loop to form a testing loop; the main control module is respectively connected with the high-frequency signal generating module and the feedback signal receiving module, and executes the nondestructive testing method to obtain the testing result of the state of the CT secondary circuit. In this embodiment, the coupling inductance is 1: the coupling inductor is provided with a signal output end and a signal input end which are respectively used for outputting high-frequency information and receiving feedback signals.
The main control module is realized through the DSP, can finish the generation of control high-frequency signals, and can judge according to the feedback signals to realize the detection of the state of the CT secondary circuit.
Specifically, when the CT secondary circuit is a path, the CT secondary circuit is equivalent to an equivalent circuit of a resistor, a capacitor, and an inductor series network, as shown in fig. 2, a spectrum characteristic diagram corresponding to the spectrum characteristic has a unique obvious resonance point. Wherein, UiIs an injected high-frequency signal, ZinIs the equivalent input impedance, ZLIn this embodiment, the impedance of the high-frequency signal input terminal is ignored for the purpose of feeding back the load impedance of the signal receiving terminal, UoIs the feedback signal returned.
Further, the equivalent input impedance Z of the equivalent circuitinComprises the following steps:
r, C, L is equivalent resistance, equivalent capacitance, and equivalent inductance of the equivalent circuit respectively;
further, the input amplitude-frequency characteristic expression is as follows:
the equivalent inductance of the equivalent circuit is:
wherein L is1Is an inductance of the secondary side of the current transformer, L2For detecting inductance of other devices in the loop, L4An inductance coupled to the primary side of the inductance, L3An inductance of the secondary side of the coupling inductance, L4Is an inductance coupled to the primary side of the inductance.
The nondestructive testing device of the present invention is generally implemented in an electric power metering system, as shown in fig. 3, in this embodiment, the nondestructive testing device is connected to the electric power metering system with a smart meter, i.e., is connected in series to a CT of a current transformer to be tested1In the CT secondary circuit, the signal output end of the coupling inductor is connected with a winding coil on the primary side of a current transformer of the intelligent electric meter in series, and the signal input end of the coupling inductor is connected with the CT of the current transformer to be tested1The winding coils of the secondary side of the transformer are connected in series. Furthermore, in this embodiment, L is2The inductance of the primary side of a current transformer of the intelligent electric meter.
When the CT secondary circuit is in poor contact, the equivalent input impedance is larger and greatly increased compared with the circuit, and the obvious resonance points in a frequency spectrum characteristic diagram are more.
When the CT secondary circuit is open circuit, the CT secondary circuit is equivalent to an open circuit, the feedback information cannot be received, and no frequency spectrum characteristic diagram exists.
When the CT secondary circuit is short-circuited, the CT secondary circuit is equivalent to a short-circuit and receives the full frequency band of the feedback signal.
In this embodiment, the nondestructive testing device further includes a loop status display module, configured to display the testing result. Specifically, the loop state display module is connected with the main control module and displays the detection result through an indicator light; the indicating lamp displays different marks corresponding to different types of CT secondary circuit states. When the circuit state display module is implemented as a plurality of indicator lamps with different colors, different CT secondary circuit states can be represented by lighting the indicator lamps with different colors; or when the circuit state display module is implemented as a dot-matrix LED, characters are displayed through the indicator lamp to show different CT secondary circuit states.
The above examples are provided only for illustrating the present invention and are not intended to limit the present invention. Changes, modifications, etc. to the above-described embodiments are intended to fall within the scope of the claims of the present invention as long as they are in accordance with the technical spirit of the present invention.
Claims (10)
1. A non-destructive testing method for the state of a CT secondary circuit is characterized in that a high-frequency signal is input in series to the CT secondary circuit and a feedback signal is received in series; judging an equivalent circuit of the CT secondary circuit according to the frequency spectrum characteristic of the feedback signal; and obtaining the states of the CT secondary circuits corresponding to the equivalent circuits of different types.
2. The method of claim 1, wherein the high frequency signal is a frequency sweep signal of 1kHz to 100kHz and the frequency is increased with equal difference.
3. The method according to claim 1, wherein when the CT secondary circuit is a path, the CT secondary circuit is equivalent to an equivalent circuit of a resistor, a capacitor, and an inductor series network, and the spectrum characteristic map corresponding to the spectrum characteristic has a unique apparent resonance point.
4. The method of claim 3, wherein the equivalent input impedance Z is the path when the CT secondary circuit is a pass-through circuitinComprises the following steps:
r, C, L is equivalent resistance, equivalent capacitance, and equivalent inductance of the equivalent circuit respectively;
further, the input amplitude-frequency characteristic expression is as follows:
5. the method of claim 4, wherein when the CT secondary circuit is in poor contact, the equivalent input impedance is larger, the equivalent input impedance is increased, and the number of distinct resonance points in the spectrum characteristic diagram is larger than that in the case of a via.
6. The method of claim 1, wherein when the CT secondary circuit is open, the CT secondary circuit is equivalent to an open circuit, the feedback information cannot be received, and there is no spectrum characteristic diagram.
7. The method of claim 1, wherein when the CT secondary circuit is short-circuited, the CT secondary circuit is equivalent to a short-circuit and receives the full frequency band of the feedback signal.
8. A nondestructive testing device for the state of a CT secondary loop is characterized by comprising a main control module, a high-frequency signal generation module, a feedback signal receiving module and a coupling inductor, wherein two ends of a primary loop of the coupling inductor are respectively connected with the high-frequency signal generation module and the feedback signal receiving module; the main control module is respectively connected with the high-frequency signal generating module and the feedback signal receiving module, and executes the nondestructive testing method of any one of claims 1 to 7 to obtain the testing result of the state of the CT secondary circuit.
9. The nondestructive testing device for the state of the CT secondary circuit as recited in claim 8, further comprising a circuit state display module, wherein the circuit state display module is connected with the main control module and displays the testing result through an indicator light; the indicating lamp displays different marks corresponding to different types of CT secondary circuit states.
10. The apparatus of claim 8, wherein when the CT secondary circuit is a pass-through, the equivalent inductance of the equivalent circuit is:
wherein L is1Is an inductance of the secondary side of the current transformer, L2For detecting inductance of other devices in the loop, L4An inductance coupled to the primary side of the inductance, L3An inductance of the secondary side of the coupling inductance, L4Is an inductance coupled to the primary side of the inductance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911193212.5A CN110850334B (en) | 2019-11-28 | 2019-11-28 | Nondestructive testing method and device for CT secondary circuit state |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911193212.5A CN110850334B (en) | 2019-11-28 | 2019-11-28 | Nondestructive testing method and device for CT secondary circuit state |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110850334A true CN110850334A (en) | 2020-02-28 |
| CN110850334B CN110850334B (en) | 2022-03-29 |
Family
ID=69606780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911193212.5A Active CN110850334B (en) | 2019-11-28 | 2019-11-28 | Nondestructive testing method and device for CT secondary circuit state |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110850334B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111650538A (en) * | 2020-05-29 | 2020-09-11 | 深圳供电局有限公司 | Electric energy meter wiring detection device and method |
| CN111650535A (en) * | 2020-05-29 | 2020-09-11 | 深圳供电局有限公司 | Electric energy meter wiring detection method |
| CN113376550A (en) * | 2021-05-31 | 2021-09-10 | 国网河南省电力公司平顶山供电公司 | PT secondary voltage return circuit detection device |
| CN113848381A (en) * | 2021-09-23 | 2021-12-28 | 石家庄科林电气股份有限公司 | Device and method for judging current bypass event |
Citations (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000041316A (en) * | 1997-09-24 | 2000-02-08 | Furukawa Electric Co Ltd:The | Method and device for wire identification |
| US6035265A (en) * | 1997-10-08 | 2000-03-07 | Reliance Electric Industrial Company | System to provide low cost excitation to stator winding to generate impedance spectrum for use in stator diagnostics |
| US6373923B1 (en) * | 1998-11-03 | 2002-04-16 | Nortel Networks Limited | Line testing method and apparatus therefor |
| CN101034130A (en) * | 2007-01-26 | 2007-09-12 | 上海欣泰通信技术有限公司 | Method and device for testing frequency domain characteristic with combined square wave sweep frequency |
| CN201876515U (en) * | 2010-11-02 | 2011-06-22 | 许继集团有限公司 | Current transformer (CT) loop anomaly detection circuit |
| CN102931684A (en) * | 2012-11-09 | 2013-02-13 | 东华大学 | Photovoltaic alternate current and direct current intelligent distribution box |
| CN103869168A (en) * | 2014-03-14 | 2014-06-18 | 云南电力试验研究院（集团）有限公司电力研究院 | Detecting and diagnosing method for secondary circuit of current transformer for electric power |
| CN104267368A (en) * | 2014-10-14 | 2015-01-07 | 国家电网公司 | Fault monitoring method for secondary circuit of metering current transformer |
| CN104849649A (en) * | 2015-05-26 | 2015-08-19 | 中国电力科学研究院 | System and method for detecting state of secondary circuit of current transformer for metering |
| CN106443304A (en) * | 2016-11-07 | 2017-02-22 | 北京博纳电气股份有限公司 | Method for detecting secondary side loop state of once metering CT on ammeter exterior and detection device |
| CN106569078A (en) * | 2016-10-25 | 2017-04-19 | 中国电力科学研究院 | State detection method and system for secondary circuit of current transformer |
| CN106645931A (en) * | 2016-11-29 | 2017-05-10 | 国网四川省电力公司电力科学研究院 | Current transformer secondary circuit monitoring module and method, and specific transformer acquiring terminal |
| CN106898901A (en) * | 2017-04-13 | 2017-06-27 | 国网福建省电力有限公司 | A kind of current terminal for reflecting current loop running status |
| CN109100603A (en) * | 2018-09-30 | 2018-12-28 | 中国电力科学研究院有限公司 | The detection device and method of secondary loop of mutual inductor short circuit |
| CN109782213A (en) * | 2018-12-21 | 2019-05-21 | 国网山西省电力公司长治供电公司 | Fault finding system and method based on secondary circuit characteristic quantity |
| CN110488137A (en) * | 2019-09-03 | 2019-11-22 | 广东电网有限责任公司 | A kind of apparatus and method detecting CT secondary circuit integrality |
-
2019
- 2019-11-28 CN CN201911193212.5A patent/CN110850334B/en active Active
Patent Citations (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000041316A (en) * | 1997-09-24 | 2000-02-08 | Furukawa Electric Co Ltd:The | Method and device for wire identification |
| US6035265A (en) * | 1997-10-08 | 2000-03-07 | Reliance Electric Industrial Company | System to provide low cost excitation to stator winding to generate impedance spectrum for use in stator diagnostics |
| US6373923B1 (en) * | 1998-11-03 | 2002-04-16 | Nortel Networks Limited | Line testing method and apparatus therefor |
| CN101034130A (en) * | 2007-01-26 | 2007-09-12 | 上海欣泰通信技术有限公司 | Method and device for testing frequency domain characteristic with combined square wave sweep frequency |
| CN201876515U (en) * | 2010-11-02 | 2011-06-22 | 许继集团有限公司 | Current transformer (CT) loop anomaly detection circuit |
| CN102931684A (en) * | 2012-11-09 | 2013-02-13 | 东华大学 | Photovoltaic alternate current and direct current intelligent distribution box |
| CN103869168A (en) * | 2014-03-14 | 2014-06-18 | 云南电力试验研究院（集团）有限公司电力研究院 | Detecting and diagnosing method for secondary circuit of current transformer for electric power |
| CN104267368A (en) * | 2014-10-14 | 2015-01-07 | 国家电网公司 | Fault monitoring method for secondary circuit of metering current transformer |
| CN104849649A (en) * | 2015-05-26 | 2015-08-19 | 中国电力科学研究院 | System and method for detecting state of secondary circuit of current transformer for metering |
| CN106569078A (en) * | 2016-10-25 | 2017-04-19 | 中国电力科学研究院 | State detection method and system for secondary circuit of current transformer |
| CN106443304A (en) * | 2016-11-07 | 2017-02-22 | 北京博纳电气股份有限公司 | Method for detecting secondary side loop state of once metering CT on ammeter exterior and detection device |
| CN106645931A (en) * | 2016-11-29 | 2017-05-10 | 国网四川省电力公司电力科学研究院 | Current transformer secondary circuit monitoring module and method, and specific transformer acquiring terminal |
| CN106898901A (en) * | 2017-04-13 | 2017-06-27 | 国网福建省电力有限公司 | A kind of current terminal for reflecting current loop running status |
| CN109100603A (en) * | 2018-09-30 | 2018-12-28 | 中国电力科学研究院有限公司 | The detection device and method of secondary loop of mutual inductor short circuit |
| CN109782213A (en) * | 2018-12-21 | 2019-05-21 | 国网山西省电力公司长治供电公司 | Fault finding system and method based on secondary circuit characteristic quantity |
| CN110488137A (en) * | 2019-09-03 | 2019-11-22 | 广东电网有限责任公司 | A kind of apparatus and method detecting CT secondary circuit integrality |
Non-Patent Citations (1)
| Title |
|---|
| 刘超超 等: "电流互感器二次侧回路状态检测装置研制", 《电测与仪表》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111650538A (en) * | 2020-05-29 | 2020-09-11 | 深圳供电局有限公司 | Electric energy meter wiring detection device and method |
| CN111650535A (en) * | 2020-05-29 | 2020-09-11 | 深圳供电局有限公司 | Electric energy meter wiring detection method |
| CN111650535B (en) * | 2020-05-29 | 2022-07-15 | 深圳供电局有限公司 | Electric energy meter wiring detection method |
| CN113376550A (en) * | 2021-05-31 | 2021-09-10 | 国网河南省电力公司平顶山供电公司 | PT secondary voltage return circuit detection device |
| CN113848381A (en) * | 2021-09-23 | 2021-12-28 | 石家庄科林电气股份有限公司 | Device and method for judging current bypass event |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110850334B (en) | 2022-03-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110850334B (en) | Nondestructive testing method and device for CT secondary circuit state | |
| CN106291123A (en) | A kind of method of direct measurement magnetic cell winding loss | |
| CN102967789B (en) | High voltage test method and device with contact point loop rapid test function | |
| CN203011948U (en) | Current transformer characteristic test secondary connection device | |
| CN103941216B (en) | Voltage transformer scene Automatic Check-out And Readiness Equipment | |
| CN103777171B (en) | A kind of method of testing of current transformer exciting characteristic curve | |
| CN202351421U (en) | Error detection device for current transformer | |
| CN205067654U (en) | A online test appearance for detecting opto -coupler | |
| CN202939230U (en) | Portable high voltage current inductor transformation ratio measuring device | |
| CN103018702A (en) | Fast checking method of high-voltage cabinet current transformer secondary loop line | |
| CN102253356A (en) | Measuring method of current transformer transformation ratio | |
| CN109283396A (en) | Ground resistance measurement method and system, the pincers resistance instrument for quantifying noiseproof feature | |
| CN104914365B (en) | A kind of detection means and method for improving Partial Discharge Detection sensitivity | |
| CN210626574U (en) | Alternating-current charging stake fault detection device | |
| CN105842578A (en) | Indicator capable of rapidly determining coaxial cable BNC radio frequency head fault types | |
| CN102955079A (en) | Portable-type high-voltage current transformer transformation-ratio measurement device | |
| CN112444689B (en) | Temperature rise test method and device for transformer | |
| CN114184863B (en) | Distribution line grounding inspection device and method by insulation resistance method | |
| CN103605001A (en) | Charged-state current secondary circuit test coupling device | |
| CN104459452B (en) | Pulse transformer dotted terminal recognizer | |
| CN204679569U (en) | The calibration equipment of current transformer | |
| CN107765127B (en) | Pin type transformer parameter testing device | |
| CN201819968U (en) | High-current partial discharge detection circuit | |
| CN114859186B (en) | Device and method for rapidly measuring minimum dielectric strength margin | |
| CN220983486U (en) | Mutual inductor testing device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |